Variable speed load balancer

ABSTRACT

A variable speed load balancer for moving loads from one location to another. The load balancer includes an overhead hoist from which the load is suspended, a control disposed remotely from the hoist for operating the hoist to raise and lower the load at varying speeds, and guide structure for connecting the control to the load for controlling lateral movement thereof during lifting and lowering. The control for the balancer includes switch means for actuating the hoist, compressive electrical resistance elements for varying its speed, movable members for actuating the switch means and resistance elements and means for precluding actuation of the resistance elements until after actuation of the switch means.

United States Patent Cordes Aug. 28, 1973 VARIABLE SPEED LOAD BALANCER Primary Examiner-Bernard A. Gilheany Assistant Examiner-W. E. Duncanson, Jr. [75] Inventor: Harry B. Cordes, York, Pa. Attorney-Dean S. Edmonds et ai.

[73] Assignee: American Chain & Cable Company,

Inc., New York, NY. [57] ABSTRACT 22 l 72 l 1 Filed Feb 9 A variable speed load balancer for moving loads from PP 223,116 one location to another. The load balancer includes an overhead hoist from which the load is suspended, a [52] Us. CL 318/257 ZOO/157 control disposed remotely from the hoist for operating [5 1] Im- CL H02p 1/22 the hoist to raise and lower the load at varying speeds, 58 Field or searc hI...".IIIIIIIIlQ 200/157 159- and guide 318/257 i load for controlling lateral movement thereof during lifting and lowering. The control for the balancer includes switch means References Cited for actuating the hoist, compressive electrical UNITED STATES PATENTS resistance elements for varying its speed, movable 3,469,164 9/1969 Truemper et al. 318 257 members for actuating the Switch means and resistance 3,509,296 4 1970 Harshman et 31.... 200/159 elements and m ans r precluding actuation of the 3,654,415 4/1972 Hawkins et al. 200/157 X resistance elements until after actuation of the switch 3,086,090 4/1963 Carroll 200/159 means,

28 Claims, 4 Drawing Figures PATENTEflwczams 375571.2 5

SHEET 1 UF 2 i, 2.. u a 1 1 I PAIENTElHucza ms SHEEI 2 (IF 2 hlr INVENTOR Harry B. Cordes ATTORNEYS VARIABLE SPEED LOAD EALANCER BACKGROUND OF THE INVENTION Presently constructed hoists, as typically used in factories and on assembly lines for material handling, assembling of parts and similar moving of loads, are equipped with controls for monitoring their movement. In one type of construction, a push button control is provided at a station where the operator stands during movement of the load. This control may be constructed to control both the vertical direction of movement of the hoist and its speed of movement. With this type of system, however, the operator is required to stay at a predetermined operating station; and since this is remote from the load being handled, he has no manual control over the load. This can be of a disadvantage where, for example, precise placement or lateral adjustment of the load is desired. Also, with the push button control used in this type of system, the speed of the hoist is varied in response simply to depression of the push buttons. This results in a very sensitive control requiring an experienced operator to assure accurate handling of loads.

In another hoisting apparatus presently available, a pneumatic control system is used. Here, an air balance pressure is preset to float the load. Movement of the load up or down is done manually by the operator. However, the force that needs to be exerted to effect movement is only a small percentage of the actual load weight due to the preset air balance pressure. This type of system has the disadvantage of requiring readjustment of the counter-balancing air pressure each time the unit is used to handle a load of different weigth. Also, the operator is still required to provide a portion of the moving force for transferring the load; and due to the direct handling of the load, the operator is in a position where injury may result if a failure of the unit should occur.

SUMMARY OF THE INVENTION In accordance with the teachings of the present invention, there is provided a load balancer having the advantages of known systems without the disadvantages thereof. Generally, the balancer includes a hoist for lifting and lowering the load, and a variable control for actuating the hoist. The control is positioned remotely of both the hoist and the load and is capable of being moved as the load is transferred from one location to another. In addition, the control, although remote from the load, is connected to the load by guide means so that the operator may control the lateral movement of the load by manually moving the control in the desired direction. With the load balancer of the present invention, the operator can critically position a load without applying any vertical force and he can handle any load from zero to maximum capacity with equal dexterity and without any preliminary adjustment or setting of the device. In addition, the load balancer does not require any air hoses or hydraulics and, thus, does not have the attendant problems of dirty air, leaking fittings and'so forth. The guide connection between the load and the remotely located control positions the operator safely away from the load and still permits him to control the load at all times during its movement.

The control used in the load balancer of the present invention is constructed with switch means for selectively actuating the hoist to produce both lifting and lowering movement. Also, the control includes compressive electrical resistance elements for controlling the speed of the hoist. These electrical resistance elements are constructed of a material which decreases in electrical resistance as it is compressed. Also, the material of the resistance elements is one in which the force required to compress it increases with the extent of compression. The actuation of the switch means and of the electrical resistance elements is controlled by depression of a trigger lever or push buttons on the control. With the improved construction, the speed of the hoist is controlled primarily as a function of pressure rather than as a function of position of the trigger lever or push buttons. With the trigger and push buttons having a small range of movement over which the speed of the hoist is varied from zero to maximum, the pressure responsive construction provides a much more sensitive control than is possible with controls where simply the extent of depression of the push button is relied upon for speed control.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the load balancer of the present invention;

FIG. 2 is a view showing the internal construction of the variable control of the load balancer shown in FIG. I as contained within a pistol grip handle;

FIG. 3 is a crosss-sectional view of an alternative embodiment of the variable control of the load balancer; and

FIG. 4 is a view of the pistol grip handle housing showing the location therein of the control mechanism constructed in accordance with FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, the load balancer is shown as generally comprising an overhead hoist l, a load holding means in the form of a hook 2, a control 3 for actuating the hoist, and guide means 4 for connecting the control to the hook. The hoist includes power means in the form of a reversible, variable speed motor 5 and suitable linkage 5' connecting it to a chain 6 suspended from the hoist. The hook 2 is carried at the lower end of the chain. The direction of movement of the hoist is controlled by the control 3 which is electrically connected to the hoist by flexible wiring 7.

In moving a load held by the hook from one location to the other, the operator holds the control 3 in one hand. As more fully described below, the control is in the shape of a pistol handle and has a trigger lever for controlling both the vertical direction of movement of the hoist and the speed of this movement. To permit the operator to move the load laterally as it is being lifted or lowered, the control 3 is movable relative to the hoist with only the flexible Wiring extending between the two. The control 33 is, however, rigidly connected to the load holding hook 2 by way of the guide 4. In construction, the guide is a rigid rod-like member forming the barrel portion of the pistol shaped control 3. As shown in FIG. 1, the guide rod is connected to the hook 2 by way of a swivel and gimbal joint 8 for providing universal movement.

Referring to FIG. 2, the piston grip handle is shown broken away to expose the pistol variable control structure used for operating of the hoist. As shown in FIG. 2, the pistol grip handle itself provided a housing 3 for the variable control. The variable control, in turn, includes a first switch 9 for controlling movement of the hoist in the up direction and a second switch 10 for controlling movement of the hoist in the down direction. In operation, depression of the contact buttons 11 and 12 of these switches turns the motor of the hoist on with the switch 9 effecting running of the motor in one direction and the switch in the reverse direction.

For controlling the speed of operation of the motor and thus the speed of the lifting and lowering movement of the hoist, two compressive electrical resistance elements are provided. The first of these elements 13 is associated with the switch 9 and controls the speed of lifting while the second of these elements 14 is associated with the switch 10 and controls the speed of lowering of the hoist.

For actuating the switches and the compressible electrical resistance elements, a two-section depressible trigger means is provided. This trigger means is comprised of a first movable means in the form of a first movable lever member 15 and a second movable means in the form of a second movable lever member 16. Both of the movable members 15 and 16 are pivotally mounted intermediate their ends to the pistol grip housing 3 at 17. The section of the movable members disposed above the pivoting axis 17 operates the switch 11 and resistance element 13 while the section of the movable members located below the axis 17 controls the switch 10 and resistance element 14. As will be seen from FIG. 2, the switches and resistance elements are disposed in the path of pivoting movement of the first and second movable members 15 and 16 for actuation thereby.

The movement of the trigger portion of the control 3 is under the influence of a plurality of springs. As shown in FIG. 2, a first spring 18 is associated with the upper section of the first movable member 15. This spring is a compression spring having one end engaging the movable member 15 and the other end backed up against the housing wall 3'. This spring functions to restrain pivoting movement of the upper section of the movable member 15 toward the switch 9. It also urges the member 15 back to its normal position shown in FIG. 2 when the depressing force is removed by the operator.

In addition to the spring 18 there is a spring 19 associated with the upper section of the members and add 16. This spring is disposed between the first movable member 15 and the second movable member 16 and functions to restrain movement of the second member toward the first member.

The compressive electrical resistance element 13 is also located between the upper sections of the movable members 15 and 16. With this positioning of element 13, it will become compressed upon pivoting of the upper section of the second movable member 16 toward the first movable member 15.

With reference to the upper section of the control the actuation of the switch 9 and the resistance element 13 in proper sequence is provided by the springs 18 and 19. More particularly, the spring 19 is of heavier construction to provide a greater restraining force than the spring 18. Thus, when the operator depresses the upper section of the trigger means by depressing the second movable member 16, this force will be transferred to the first movable member 15 without causing relative movement between the two members. When the second movable member contacts the button 11 of the switch 9 and bottoms out, further depressing of the member 16 will cause it to pivot toward the first member 15. This, in turn, will cause compression of the resistance element 13 with resulting control of the speed of movement of the hoist.

The above description has only been of the upper section of the control. It will be understood, however, that the bottom section will be similarly constructed with switch 10, element 14 and springs 20 and 21 functioning in the same way as their counterparts in the upper section of the control.

Each of the electrical resistance elements is constructed of electrically resistive material which varies in resistance in proportion to the extent of compression. Also, the material is one upon which the force required to compress it increases directly with an increase in the compression. The material may, for example, be a urethane foam in which conductive material is embedded. Suitable resistance elements are manufactured by the Sensotec Division of Scientific Advances, Inc.

The specifications for a cylindrically shaped resistance element having a 0.5 inch diameter and a length of 0.4 inches with metal inch tabs would be as follows:

Young's modulus 30 pounds/sq. in.

Power dissipation 2 watt/element (Maximum) Resistance approximately 600 ohms uncompressed.

Linearity, I-Iysterisis & Repeatability about i 10 percent.

Temperature withstand: 200 F maximum.

Frequency response: 3 cycles per minute.

The electrical resistance elements are electrically connected to the motor 5 of the hoist so that compression thereof will vary the current to the control circuit for the motor and thus vary the speed of the motor. The speed control is in response to pressure exerted on the trigger portion of the control 3. The operator simply needs to depress the upper section of the trigger for effecting a raising of the hoist and controlling the speed of raising while depression of the lower section results in a similar but reverse movement of the hoist.

FIG. 3 shows an alternative embodiment of the variable control which may be used in substitution for that shown in FIG. 2. In FIG. 3 only one section of the variable control is shown. Two sections of the type shown in FIG. 3 would be included in the pistol grip handle to effect both raising and lowering of the hoist. The control shown in FIG. 3 is of the push button or plunger type as opposed to the pivoting trigger type shown in FIG. 2. FIG. 4 shows a view of the pistol grip handle with the up and down push buttons being located for actuation by the thumb of the operator as he grips the handle.

Referring to FIG. 3, the variable control comprises a switch 22 adapted to be electrically connected to the motor 5 for turning it on to operate the hoist in one direction. The control also includes a compressive electrical resistance element 23 of the same construction as the resistance elements 13 and 14. This resistance element is electrically connected to the control circuit to the motor 5 to control the speed in the same way as the resistance elements 13 and 14 function.

The control shown in FIIG. 3 is provided with a first movable member 24 having a first end 25 and a second end 26. The end 25 is movable toward the switch 22 to actuate the switch and the end 26 is adapted to move toward the electrical resistance element 23 to cause compression thereof. Advantageously, the end 26 is operatively connected to the resistance element by a second movable member 27. This member has a spherical top 28 on which the end 26 of the first movable member 25 rests so as to provide a pivotal connection theretween The end 25 of the member 24 broadly defines a first movable means for actuating the switch 22 while the end 26 of the member 24 with or without the second movable member 27 broadly defines a second movable means for actuating the element 23. The structure of the control so far described is all enclosed within a housing 29. This housing may define the housing of the pistol grip handle or may define a separate sub-unit for mounting within the handle housing 3.

For actuating the control and for effecting depression of the movable member 24, a depresible push button assembly 30 is provided. This assembly is comprised of a plunger 31 extending outwardly of the housing 29 through an opening 32. The plunger is capped by a push button 33 which is mounted for sliding movement within a guide structure 34 fixed to the housing 29. The lower end of the plunger is of reduced cross-sectional shape and extends through an opening 35 in the movable member 24 intermediate the two ends 25 and 26. The shoulder 36 formed by the reduced portion of the plunger engages the member 24 and-prevents movement of the upper part of the plunger through the opening 35.

In order to preclude actuation of the resistance element 23 until after the switch 22 has been actuated, springs 37 and 38 are provided. Spring 37 functions to restrain movement of the meember 24 toward the contact button 22 of the switch 22 while spring 38 functions to restrain movement of the member 27 into compressive engagement with the resistance element 23. The size of the springs is such that the spring 38 provides a greater restraining force against the movement of the member 27 than does the spring 37 against movement of the end 25 of member 24.

In operation, depression of the push button 33 causes depression of the plunger 31. This, in turn, causes the member 24 to first pivot about the pivotal connection 28 and end 25 to engage and depress button 22 of the switch 22. As this movement of the memmber 24 bottoms out, which happens after the button 22 is fully depressed, continued depression of the push button .33 causes the end 26 of the member 24 to be depressed. This, in turn, causes depression of the movable member 27 against the restraining forces of the spring 38 to effect the desired compression of the resistance element 23 and thus the control of the speed of the motor 5. With two of the control sections of FIG. 3 incorporated into the pistol grip handle housing 3', complete control of the hoist is provided with the same advantages as present in the construction of FIG. 2.

I claim:

1. A load balancer comprising:

a. an overhead hoist having a power means and load holding means suspended therefrom for vertical movement in response to actuation of said power means;

b. control means for actuating said power means, said control means being positioned at a location remote from both said hoist and said load holding means and being movable relative to said hoist; and

c. guide means connecting said control means to said load holding means for guiding the lateral movemment thereof during vertical movement.

2. A load balancer according to claim 1 wherein:

a. said power means includes a reversible lifting means; and

b. said control means includes switch means for reversing the direction of said lifting means to selectively raise and lower said load holding means.

3. A load balancer according to claim 2 wherein:

a. said guide means includes a rigid rod-like member.

4. A load balancer according to claim 3 wherein:

a. said guide means includes a swivel and gimbal joint connecting the rod-like member to the load holding means.

5. A load balancer according to claim 2 wherein:

a. said control means includes a pistol grip handle with a two-section depressible means; and

b. said switch means includes:

1. a first switch for actuating said lifting means to raise said load holding means, said first switch being disposed in the path of movement of a first section of said means for actuation thereby; and

2. a second switch for actuating said lifting means to lower said load holding means, said second switch being disposed in the path of movement of the second section of said depressible means for actuation thereby.

6. A load balancer according to claim 5 wherein:

a. said depressible means includes a two-way pivotable trigger means mounted for pivoting movement intermediate its ends with said one section being defined by one end of said trigger means and the other section by the other end thereof.

7. A load balancer according to claim 6 wherein:

a. said motor is a variable speed motor; and

b. said control means further includes:

1. a first compressible electrical .resistance element disposed in the path of movement of said trigger means when pivoted in a first direction for com pression thereby, said first element being constructed of electrically resistive material which varies in resistance in proportion to the extent of compression thereof,

2. means for electrically connecting assent first element to said lifting means to control the current to the lifting means and the speed of assent of said load holding means,

3. a second compressible electrical resistance element disposed in the path of movement of said trigger means when pivoted in a second direction for compression thereby, said second element being constructed of electrically resistive material which varies in resistance in proportion to the extent of compression thereof, and

4. means for electrically connecting said second element to said lifting means to control the current to the lifting means and the speed of descent of said load holding means.

8. A load balancer according to claim 7 wherein:

a. said trigger means includes:

1. a first movable member pivotally mounted intermediate its ends for movement of one end thereof toward said first switch for actuating said first switch and the other end thereof toward said second switch for actuating said second switch,

2. a second movable member pivotally mounted intermediate its ends on the side of the first movable member opposite said switches for move ment of one end thereof toward the one end of said load holding means, 3. a second compressible electrical resistance element disposed in the path of movement of said depressible means for actuation when said second push button means is depressed, said second element being constructed of electrically resistive material which varies in resistance in propor-,

said first movable member and the other end tion to the extent of depression thereof, thereof toward the other end of said first mov- 4. means for electrically connecting said second elable member; ement to said lifting means to control the current b. said first and second electrical resistance elements to the lifting means and the speed of descent of are positioned between said first and second movthe load holding means, and

able members with the first element adjacent the 10 5. means for precluding compression of said first one end of said members and the second element electrical element until after actuation of said adjacent the other end thereof; and first switch and for precluding compression of c. said control means further includes spring means said second electrical element until after actuafor precluding movement of said second movable tion of said second switch.

member into compressive engagement with said 13. A load balancer according to claim 12 wherein:

electrical resistance elements until after movement a. said electrical resistance elements are constructed of said first member into contact with said switch of material upon which the force required to commeans to actuate said switch means. press the material increases directly with an in- 9. A load balancer according to claim 8 wherein: said crease in compression thereof. spring means includes: 14. A variable control for controlling operation of an a. a first spring for restraining movement of the one electrical device by varying the current supplied end of said first movable member toward said first thereto comprising: switch; a. a switch electrically connected to said electrical b. a second spring positioned between said first and device for turning said device on and off;

second movable members adjacent the one end b. first movable means mounted for movement into thereof for restraining movement of the one end of contact with said switch to actuate said switch;

said second member toward the first movable c. a compressible electrical resistance element conmember, said spring spring providing a greater restructed of electrically resistive material which varstraining force than said first spring; ies in resistance in proportion to the extent of comc. a third spring for restraining movement of the pression thereof;

other end of said first movable member toward said d. means for electrically connecting said resistance second switch; and element to said electrical device to control the curd. a fourth spring positioned between said first and rent supplied thereto in response to the extent of second movable members adjacent the other end compression of said resistance element;

thereof for restraining movement of the other end e. second movable means mounted for movement of said second member toward said first member, relative to said resistance element to compressively said fourth spring providing a greater restraining contact said resistance element; and

force than said third spring. f. means for precluding relative movement between 10. A load balancer according to claim 9 wherein: said second movable means and said electrical rea. said electrical resistance elements are constructed sistance element until after movement of said first of material upon which the force required to commovable means into contact with said switch means press the material increases directly with an into actuate said switch means.

crease in compression thereof. 15. A variable control according to claim 14 wherein 11. A load balancer according to claim 5 wherein: said means for precluding movement of said second a. said depressible means includes first and second movable means includes:

depressible push button means positioned on the a. first restraining means for restraining movement of back side of the pistol grip handle for actuation by said first movable means into contact with said the thumb of the operator, the one section of said switch; and

depressible means being defined by the first push b. second restraining means for restraining movebutton means and the second section by the second ment of said second movable means into comprespush button means. sive engagement with said electrical resistance ele- 12. A load balancer according to claim 11 wherein: ment, said second restraining means providing a a. said motor is a variable speed motor; greater restraining force than said first restraining b. said control means further includes: means.

1. a first compressible electrical resistance element 16. A variable control according to claim 15 wherein: disposed in the path of movement of said dea. said first and second restraining means are springs. pressible means for actuation when said first 17. A variable control according to claim 16 wherein: push button means is depressed, said first elea. said electrical resistance element is constructed of ment being constructed of electrically resistive 0 material upon which which the force required commaterial which varies in resistance in proportion press compress the material increased directly with to the extent of compression thereof, an increase compression compression thereof.

2. means for electrically connecting said first ele- 18. A variable control for controlling operation of an ment to said lifting means to control the current electrical device by varying the current supplied to the lifting means and the speed of assent of thereto comprising:

a. a switch electrically connected to said electrical device for turning said device on and off; b. a first movable member mounted for movement into contact with said switch to actuate said switch;

c. a second movable member spaced from said first member on the side thereof opposite said switch means;

d. a compressible electrical resistance element positioned between said first and second movable members for compression upon relative movement between said second member and said first member toward each other, said resistance element being constructed of electrically resistive material which varies in resistance in proportion to the extent of compression thereof;

e. means for electrically connecting said resistance element to said electrical device to control the current supplied thereto in response to the extent of compression of said resistance element; and

f. means for precluding relative movement between said first and second movable members to compress said electrical resistance element until after movement of said first member into contact with said switch means.

19. A variable control according to claim 18 wherein said means for precluding movement of said second member includes:

a. first spring means for restraining movement of said first member into contact with said switch; and

b. second spring means positioned between said first and second members for restraining movement of said second member toward said first member, said second spring means providing a greater restraining force than said first spring means.

20. A variable control according to claim 19 wherein:

a. said electrical resistance element is constructed of material upon which the force required to compress the material increases directly with an increase in compression.

21. A variable control according to claim 20 wherein said electrical device is a variable speed, reversible, motor driven device the speed of which varies with the varying of current supplied thereto, further comprising:

a. a support housing;

b. means for pivotally mounting said first and second movable members intermediate their ends on said support housing with said switch, electrical resistance element and said first and second springs positioned to cooperate with one end of said first and second movable members;

c. means for electrically connecting said switch to said motor for controlling operation of said device in one direction;

d. a second switch and said electrical resistance element and third and forth springs positioned to cooperate with the other end of said first and second movable members in the same manner as the first mentioned switch, resistance element and springs cooperate with the one end of said first and second movable members; and

e. means for electrically connecting said second switch to said motor for controlling operation of said device in a direction opposite said one direction.

22. A variable control according to claim 21 wherein:

a. said housing is in the shape of a pistol grip handle enclosing said switches, first movable member, electrical resistance elements and springs; and

5 electrical device by varying the current supplied thereto comprising:

a. a switch electrically connected to said electrical device for turning said device on and off;

b. a compressible electrical resistance element constructed of electrically resistive material material which varies in resistance in proportion to the extent of compression thereof;

c. means for electrically connecting said resistance element to said electrical device to control the current supplied thereto in response to the extent of compression of said resistance element; 1

d. a first movable member pivotally mounted for movement of one end toward said switch to actuate said switch and the other end toward said electrical resistance element to cause compression thereof; and

e. means for precluding movement of said other end toward said electrical resistance element to cause compression thereof until after movement of said one end toward said switch to actuate said switch.

24. A variable control according to claim 23 further comprising:

said means for precluding movement of said second movable member includes:

comprising:

a. push button means disposed intermediate the ends of said first movable member for moving said first and second movable members toward said switch and electrical resistance element, respectively, upon depression thereof; and

b. a housing enclosing said first and second movable members and said switch and electrical resistance elements, with said push button means extending through said housing for actuation.

28. A variable control according to claim 27 wherein:

a. said first spring means engages said first movable member intermediate the ends thereof and acts on said push button means to restrain depression thereof; and

b. said second spring means engages said second movable member.

I it i 8 9 UNITED STATES PATENT 'UFFICE CERTIFICATE OF CORRECTION Patent No. 55,725 DatedAugust 28, 1973 Inventor(s) Harry B; Cordes It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 65, "the piston grip" should read the pistol line 66, '"expose the pistol variable" should read expose the internal variable-. Column 3, line 48, "members and add 16" should read members line 49, 15 and l6.-. Column 4 line 25, "metal inch tabs" should read metal end tabs--. Column 5, line 7, "tween The end" should read therebetween.

line 8, The 'end-; line 18, "a depresible" should read --a depressible-, line 34, "the meember 24" should read the member 24. Column 6, line 2; "lateral movem" should read -lateral moveline 23, "said means" should read sai'd depressible means-;

Column 7, line 19, "8 wherein: said" should read 8 wherein said-; line 28, "said spring spring" should read said second spring--;

Column 9, line 51, "second switch and said electrical" should read second switch and second electrical-- line 53, "and forth springs" should read and .A fourth springs. Column 10, line 10, "resistive material material" should read resistive material.

Signed and sealed this 26th day of March 19m.

(SEAL) Attest: I v

EDWARD IVLFLETCHERJR. c. MARSHALL DANN Attesting Officer Commissioner of Patents OHM po'mso (10459) uscoMM-Dc scan-P69 Q U.S. GOVERNMENT PRINTING OFFICE: I969 0-366-334,

UNITED STATES PATENT @FFICE CERTIFICATE 9F CGRRECTWN Patent No. 3 755 725 DatedAugust 28 197.?

Inventor(s) Harry B. Cordes It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 65, "the piston grip" should read the pistol p"; line 66, "expose the pistol variable" should read expose the internal variable. Column 3, line 48, "members and add 16" should read members line 49, 15 and l6-. Column 4, line 25, "metal inch tabs" should read metal end tabs-. Column 5, line 7, "tween The end" should read therebetween.

line 8, The -end-; line 18, "a depresible" should read a depressible-- line 34, "the meember 24" should read the member 24. Column 6, line "lateral movem" should read lateral moveline 23, "said means" should read said depressible means;

Column 7, line 19, "8 wherein: said" should read 8 wherein said-; line 28, "said spring spring" should read said second spring- Column 9, line 51, "second switch and said electrical" should read second switch and second electrical-- line 53, "and forth springs" should read and fourth springs. Column 10, line 10, "resistive material material" should read resistive material.

Signed and sealed this 26th day of March 19m.

(SEAL) Attest: I

EDE'IARD I LFLETCHERJR. C. MARSHALL DANN Attesting Officer Commissioner of Patents USCOMM-DC 6O376P59 U.S, GOVERNMENT PRINTING OFFICE: I959 0-366-334,

)RM PO-IOSO (was) Q 

1. A load balancer comprising: a. an overhead hoist having a power means and load holding means suspended therefrom for vertical movement in response to actuation of said power means; b. control means for actuating said power means, said control means being positioned at a location remote from both said hoist and said load holding means and being movable relative to said hoist; and c. guide means connecting said control means to said load holding means for guiding the lateral movemment thereof during vertical movement.
 2. a second switch for actuating said lifting means to lower said load holding means, said second switch being disposed in the path of movement of the second section of said depressible means for actuation thereby.
 2. a second movable member pivotally mounted intermediate its ends on the side of the first movable member opposite said switches for movement of one end thereof toward the one end of said first movable member and the other end thereof toward the other end of said first movable member; b. said first and second electrical resistance elements are positioned between said first and second movable members with the first element adjacent the one end of said members and the second element adjacent the other end thereof; and c. said control means further includes spring means for precluding movement of said second movable member into compressive engagement with said electrical resistance elements until after movement of said first member into contact with said switch means to actuate said switch means.
 2. means for electrically connecting assent first element to said lifting means to control the current to the lifting means and the speed of assent of said load holding means,
 2. means for electrically connecting said first element to said lifting means to control the current to the lifting means and the speed of assent of said load holding means,
 2. A load balancer according to claim 1 wherein: a. said power means includes a reversible lifting means; and b. said control means includes switch means for reversing the direction of said lifting means to selectively raise and lower said load holding means.
 3. A load balancer according to claim 2 wherein: a. said guide means includes a rigid rod-like member.
 3. a second compressible electrical resistance element disposed in the path of movement of said depressible means for actuation when said second push button means is depressed, said second element being constructed of electrically resistive material which varies in resistance in proportion to the extent of depression thereof,
 3. a second compressible electrical resistance element disposed in the path of movement of said trigger means when pivoted in a second direction for compression thereby, said second element being constructed of electrically resistive material which varies in resistance in proportion to the extent of compression thereof, and
 4. means for electrically connecting said second element to said lifting means to control the current to the lifting means and the speed of descent of said load holding means.
 4. means for electrically connecting said second element to said lifting means to control the current to the lifting means and the speed of descent of the load holding means, and
 4. A load balancer according to claim 3 wherein: a. said guide means includes a swivel and gimbal joint connecting the rod-like member to the load holding means.
 5. means for precluding compression of said first electrical element until after actuation of said first switch and for precluding compression of said second electrical element until after actuation of said second switch.
 5. A load balancer according to claim 2 wherein: a. said control means includes a pistol grip handle with a two-section depressible means; and b. said switch means includes:
 6. A load balancer according to claim 5 wherein: a. said depressible means includes a two-way pivotable trigger means mounted for pivoting movement intermediate its ends with said one section being defined by one end of said trigger means and the other section by the other end thereof.
 7. A load balancer according to claim 6 wherein: a. said motor is a variable speed motor; and b. said control means Further includes:
 8. A load balancer according to claim 7 wherein: a. said trigger means includes:
 9. A load balancer according to claim 8 wherein: said spring means includes: a. a first spring for restraining movement of the one end of said first movable member toward said first switch; b. a second spring positioned between said first and second movable members adjacent the one end thereof for restraining movement of the one end of said second member toward the first movable member, said spring spring providing a greater restraining force than said first spring; c. a third spring for restraining movement of the other end of said first movable member toward said second switch; and d. a fourth spring positioned between said first and second movable members adjacent the other end thereof for restraining movement of the other end of said second member toward said first member, said fourth spring providing a greater restraining force than said third spring.
 10. A load balancer according to claim 9 wherein: a. said electrical resistance elements are constructed of material upon which the force required to compress the material increases directly with an increase in compression thereof.
 11. A load balancer according to claim 5 wherein: a. said depressible means includes first and second depressible push button means positioned on the back side of the pistol grip handle for actuation by the thumb of the operator, the one section of said depressible means being defined by the first push button means and the second section by the second push button means.
 12. A load balancer according to claim 11 wherein: a. said motor is a variable speed motor; b. said control means further includes:
 13. A load balancer according to claim 12 wherein: a. said electrical resistance elements are constructed of material upon which the force required to compress the material increases directly with an increase in compression thereof.
 14. A variable control for controlling operation of an electrical device by varying the current supplied thereto comprising: a. a switch electrically connected to said electrical device for turning said device on and off; b. first movable means mounted for movement into contact with said switch to actuate said switch; c. a compressible electrical resistance element constructed of electrically resistive material which varies in resistance in proportion to the extent of compression thereof; d. means for electrically connecting said resistance element to said electrical device to control the current supplied thereto in response to the extent of compression of said resistance element; e. second movable means mounted for movement relative to said resistance element to compressively contact said resistance element; and f. means for precluding relative movement between said second movable means and said electrical resistance element until after movement of said first movable means into contact with said switch means to actuate said switch means.
 15. A variable control according to claim 14 wherein said means for precluding movement of said second movable means includes: a. first restraining means for restraining movement of said first movable means into contact with said switch; and b. second restraining means for restraining movement of said second movable means into compressive engagement with said electrical resistance element, said second restraining means providing a greater restraining force than said first restraining means.
 16. A variable control according to claim 15 wherein: a. said first and second restraining means are springs.
 17. A variable control according to claim 16 wherein: a. said electrical resistance element is constructed of material upon which which the force required compress compress the material increased directly with an increase compression compression thereof.
 18. A variable control for controlling operation of an electrical device by varying the current supplied thereto comprising: a. a switch electrically connected to said electrical device for turning said device on and off; b. a first movable member mounted for movement into contact with said switch to actuate said switch; c. a second movable member spaced from said first member on the side thereof opposite said switch means; d. a compressible electrical resistance element positioned between said first and second movable members for compression upon relative movement between said second member and said first member toward each other, said resistance element being constructeD of electrically resistive material which varies in resistance in proportion to the extent of compression thereof; e. means for electrically connecting said resistance element to said electrical device to control the current supplied thereto in response to the extent of compression of said resistance element; and f. means for precluding relative movement between said first and second movable members to compress said electrical resistance element until after movement of said first member into contact with said switch means.
 19. A variable control according to claim 18 wherein said means for precluding movement of said second member includes: a. first spring means for restraining movement of said first member into contact with said switch; and b. second spring means positioned between said first and second members for restraining movement of said second member toward said first member, said second spring means providing a greater restraining force than said first spring means.
 20. A variable control according to claim 19 wherein: a. said electrical resistance element is constructed of material upon which the force required to compress the material increases directly with an increase in compression.
 21. A variable control according to claim 20 wherein said electrical device is a variable speed, reversible, motor driven device the speed of which varies with the varying of current supplied thereto, further comprising: a. a support housing; b. means for pivotally mounting said first and second movable members intermediate their ends on said support housing with said switch, electrical resistance element and said first and second springs positioned to cooperate with one end of said first and second movable members; c. means for electrically connecting said switch to said motor for controlling operation of said device in one direction; d. a second switch and said electrical resistance element and third and forth springs positioned to cooperate with the other end of said first and second movable members in the same manner as the first mentioned switch, resistance element and springs cooperate with the one end of said first and second movable members; and e. means for electrically connecting said second switch to said motor for controlling operation of said device in a direction opposite said one direction.
 22. A variable control according to claim 21 wherein: a. said housing is in the shape of a pistol grip handle enclosing said switches, first movable member, electrical resistance elements and springs; and b. said second movable member defines an elongated trigger grip operably positioned for actuation externally of said housing.
 23. A variable control for controlling operation of an electrical device by varying the current supplied thereto comprising: a. a switch electrically connected to said electrical device for turning said device on and off; b. a compressible electrical resistance element constructed of electrically resistive material material which varies in resistance in proportion to the extent of compression thereof; c. means for electrically connecting said resistance element to said electrical device to control the current supplied thereto in response to the extent of compression of said resistance element; d. a first movable member pivotally mounted for movement of one end toward said switch to actuate said switch and the other end toward said electrical resistance element to cause compression thereof; and e. means for precluding movement of said other end toward said electrical resistance element to cause compression thereof until after movement of said one end toward said switch to actuate said switch.
 24. A variable control according to claim 23 further comprising: a. a second movable member connecting the other end of said first movable member to said electrical resistance element; and b. means for pivotally connecting said second movable member tO said other end.
 25. A variable control according to claim 24 wherein: a. said electrical resistance elements are constructed of material upon which the force required to compress the material increases directly with an increase in compression thereof.
 26. A variable control according to claim 25 wherein said means for precluding movement of said second movable member includes: a. a first spring means for restraining movement of said first movable member toward said switch; and b. a second spring means for restraining movement of said second movable member into compressive engagement with said electrical resistance element, said second spring means providing a greater restraining force than said first spring means.
 27. A variable control according to claim 26 further comprising: a. push button means disposed intermediate the ends of said first movable member for moving said first and second movable members toward said switch and electrical resistance element, respectively, upon depression thereof; and b. a housing enclosing said first and second movable members and said switch and electrical resistance elements, with said push button means extending through said housing for actuation.
 28. A variable control according to claim 27 wherein: a. said first spring means engages said first movable member intermediate the ends thereof and acts on said push button means to restrain depression thereof; and b. said second spring means engages said second movable member. 